Firmware and setup
Karu runs PX4 using the board target px4_fmu-v6xrt_default. ArduPilot is unsupported as it has no port for the
i.MX RT processor family.
Tested PX4 versions
- v1.17.0
- v1.18.0-rc1 (fca3df865) (Improves CAN reliability)
Flashing
Flashing with QGroundControl
- In QGroundControl open Vehicle Setup, then Firmware.
- Then connect the USB-C port straight to the computer. Do not use a USB hub.
- Choose PX4 and a version from the list above.
- Wait for the progress bar to finish. The board reboots and reconnects.
Flashing from the command line
- Connect the USB-C port straight to the computer. Do not use a USB hub.
- From a PX4 source tree run the following:
make px4_fmu-v6xrt_default upload
Serial ports
| UART | Device | Port | PX4 default |
|---|---|---|---|
| UART1 | /dev/ttyS0 | FMU DEBUG | system console |
| UART3 | /dev/ttyS1 | GPS1 | GPS |
| UART4 | /dev/ttyS2 | TELEM1 | MAVLink |
| UART5 | /dev/ttyS3 | GPS2 | second GPS |
| UART6 | /dev/ttyS4 | RC IN / AUX | RC input |
| UART8 | /dev/ttyS5 | TELEM2 | free |
| UART10 | /dev/ttyS6 | TELEM3 | free |
| UART11 | /dev/ttyS7 | UART & I2C | free |
Sensors and redundancy
Three IMUs
PX4 runs one estimator on one IMU by default with the other two IMUs serving as failover fallback.
To run three estimators, one per IMU:
- Set
SENS_IMU_MODEto 0 and reboot. - Set
EKF2_MULTI_IMUto 3 and reboot.
Internal compass
The module has a BMM350 magnetometer. With an external compass on GPS1, PX4 prefers the external one.
Current through the vehicle disturbs the internal compass. The PX4 compass power compensation page explains how to improve this.